chore: add documentation linter (#206)

Author: karenc-bq

.github/styles/vocab.txt

@@ -0,0 +1,3 @@
+(?i)Failover
+(?i)Postgres.*
+(?i)Psycopg

.github/workflows/vale.yml

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+name: Document Linter
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - '*'
+
+jobs:
+  vale:
+    name: Documentation Linter using Vale
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: errata-ai/vale-action@reviewdog

.vale.ini

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+StylesPath = .github/styles
+MinAlertLevel = suggestion
+
+[*.md]
+BasedOnStyles = Vale